1. Field of the Invention
The present invention relates generally to seed metering mechanisms for planters. Specifically, the invention relates to a seed metering apparatus that regulates and restricts the unintended dispensation of seeds thereby minimizing the waste or loss of seed and increasing the precision of seed placement. More specifically, the invention relates to an apparatus that provides precise and reliable regulation of seed placement without disrupting the operation of a conventional seed meter.
2. Description of the Prior Art
Mechanical seed meters are well known in the art, as are seed meters that operate under a vacuum all of which have the objective of ensuring that seeds are singularly dispensed. These meters, however, while useful for their intended purpose do not optimally control and regulate discharge of seeds to the degree necessary for efficient and precise farming operations. The general structure of a seed meter includes a seed well to keep seeds and a seed plate comprising openings and working in conjunction with a vacuum to associate seeds from the seed well with the openings. Usually the openings are near the seed plate's perimeter which is typically circular. The plate is rotated through the seed well and then around to a discharge chute where the vacuum pressure is removed and the force of gravity urges the seed's discharge either directly onto the ground or indirectly via a chute and/or seed tube. There is no opportunity to stop mid-pathway once the seed is discharged from the seed plate. Hence, it is incumbent on the operator to precisely time the shut-down of the seed meter with the speed and stopping distance of the tractor at the end of a planting row or upon encountering a planting border or other obstacle. Without appropriate timing, the meter is likely to double plant or skip.
If a conventional seed meter is shut down while an implement is still in motion, a number of seeds may still be dispensed. This happens because although the drive mechanism is interrupted, it is common for seed plates to rotate up to an additional ⅙ of a complete rotation (˜60°) thereafter the exact degree of extra rotation depends on such factors as speed, gearing, clutch operation, row-shutoff mechanism, etc. By design, a rotating seed plate will continue to dispense seeds according to its mode or mechanism of operation therefore resulting in multiple simultaneously discharged seeds. Upon restarting movement following a shut-down, the seed plate must be primed by spinning to refill; seeds can be discharged during this process. Skips or blanks i.e. a space where a plant should grow but does not because no seed was planted may occur if the seed plate is not appropriately constructed both to agitate the seed mass which assists the seeds to become associated with the plate via the vacuum pressure, and to adequately hold seeds in place on the plate.
Many seed meters' mechanisms depend on air clutches and air compressors. These clutches and compressors are prone to failure under the conditions typical for seed meters. Specifically, dirt, dust and moisture create a situation where air clutches and compressors become less and less reliable.
The price of seed and the growth inefficiencies represented by the lack of control inherent in most conventional seed meters would probably have gone unnoticed fifteen or twenty years ago, but today's farmer cannot afford to ignore this issue. Genetically modified and other specially bred seeds are very expensive. Further, the application of herbicides and pesticides add to the expense and can be controlled to very minute degrees. However, having such control over and understanding of specific application rates of fertilizers or chemicals can be negated by double plantings or irregular spacing of plants. Any time seeds are wasted or chemicals are over or under applied represents a change in income for agricultural operators.
A need exists for an improved seed meter that selectively and precisely controls the dispensation of seed at the control of an operator. A further need exists for an improved meter that conserves any metered and released but un-discharged seeds and returns them to a seed reservoir or container for subsequent metering and planting. Meters that more dependably meter seeds would be advantageous. Finally, it would be desirable to accomplish these goals in a manner that does not increase maintenance requirements and downtime.